Display control apparatus has been well known for use in controlling the display of video information by a display device such as a liquid crystal display panel. In this regard, modern personal computers usually contain a video drive module adapted to be coupled to a video monitor to communicate information necessary to create an image on the screen of the monitor. For example, reference may be made to the following U.S. Pat. Nos.: 4,652,101; 4,812,034; 4,846,694; 4,880,303; 4,882,599; 4,944,578; 4,953,971; 4,976,536; 5,041,965; and 5,101,197.
While such display control apparatus may have been satisfactory for many applications, it would be highly desirable to have a display control apparatus which would enable a display controller for a display device to initiate independent control functions, even while an image is in the process of being displayed.
As an example of such an application, liquid crystal display panels have been driven remotely by personal computers, so that the image formed by the display panel, can be projected onto a large screen or a wall. In this manner, computer generated images, produced by the personal computer, can be projected by an overhead projector onto a suitable viewing surface to permit a large number of persons to view the computer information. For example, reference may be made to the prior mentioned patent applications.
It would be highly desirable to enable the computer to communicate with the display panel even while it is generating an image. By so doing, control signals or commands could be utilized by the display panel for other functions. For example, while an image is being generated by the display panel, the computer could send a command to cause the display image to be altered, or to remain unchanged.
Such a new display control apparatus should be able to be used, without the necessity of providing special cabling or ports. Also, such an apparatus should be relatively inexpensive to manufacture, and convenient to use.